Add and subtract times in days, hours, minutes and seconds, or add time to a date and clock time to see when something ends. Every answer also comes as total hours, minutes and seconds.
Two calculators in one
- Add or subtract times: total up video lengths, race splits, flight legs or time spent on tasks, and take time away. Add as many rows as you need, and mix days, hours, minutes and seconds; decimals like 1.5 hours work too.
- Date and time ± time: find when a 36-hour job finishes, what time it was 90 minutes ago, or the date and time 72 hours from now.
How it works
Each time is turned into seconds: days × 86,400 + hours × 3,600 + minutes × 60 + seconds. The seconds are added or subtracted, then split back into days, hours, minutes and seconds. The totals are the same number of seconds divided by 86,400 (days), 3,600 (hours) or 60 (minutes).
Worked examples
2 h 45 min 30 s + 1 h 30 min 45 s = 9,930 s + 5,445 s = 15,375 s = 4 h 16 min 15 s. That's 256.25 minutes, or 4.2708 hours.
Friday 2 October 2026 at 09:30 + 1 day 2 h 30 min = Saturday 3 October 2026 at 12:00.
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Frequently asked questions
How do I add hours and minutes together?
Add the minutes, and for every 60 minutes carry 1 hour; then add the hours. For example, 2 h 45 min + 1 h 30 min = 3 h 75 min = 4 h 15 min. The calculator does the carrying for days, hours, minutes and seconds at once.
How do I subtract one time from another?
Turn both into seconds (or minutes), subtract, and turn the answer back into hours and minutes. In the calculator, switch the second time to Subtract. If the answer is negative it's shown with a minus sign, such as −1 h 30 min.
How do I convert minutes to decimal hours?
Divide by 60. So 30 minutes is 0.5 hours, 45 minutes is 0.75 hours, and 4 h 16 min 15 s is 256.25 minutes ÷ 60 = 4.2708 hours. Every result here also shows the total in days, hours, minutes and seconds.
What time will it be 72 hours from now?
Choose 'Date and time ± time'. The start fills in with today's date and the current time; enter 72 in Hours (or 3 in Days) and read the result. Use Subtract to go back in time instead.
Does it allow for daylight saving time?
No. It counts clock time as written, so adding 24 hours always gives the same clock time the next day. If a daylight-saving change falls in between, the real elapsed time is an hour more or less.
How is this different from the hours calculator?
The hours calculator works out the time between two clock times, such as a shift from 09:30 to 18:15 with a break, and adds up a week's timesheet. This time calculator adds and subtracts amounts of time and moves a date and time forward or back.